/}  /7/  TO 


U.S.  DEPARTMENT  OF  AGRICULTURE, 

Bl  REA1     i  IF  PLANT   INDUSTRY-  (uvular  No.  3. 

B.  T.  GALLOWAY,  Chief  of  Bureau. 


SOME  STEM  TUMORS  OR  KNOTS  ON  APPLE 
AND  QUINCE  TREES. 


GEORGE  G.   HEDGCOCK,  Scientific   Assistant, 
[nvestigations  of   Diseases  of  Fruits. 


GOVEH-.  N  .  1908 


DEPOSITORY 


Digitized  by  the  Internet  Archive 
in  2013 


http://archive.org/details/tumorsorOOunit 


Bl  Rl  LI    OF  PLANT  INDUSTRY. 

:  :    Galloway. 

•  r:  F.  Woods. 
'■mi  Pathology,  Erwin  F.  Smith.  Pathologist  in  Charg 

s  - 
~en  Metcalf.  Pathologist  in  C 
nd  Plant  :am  A.  Orton.  Pathologist  in  I 

T.  Swingle.  siologist  i- 

Cotton  Breeding  Investigations,  Archibald  D.  Shamel  and  Daniel  X.  Shoemaker.  Physiolo- 
- 

Archibald    D.    Shamel.    Wightman    W.    Garner,    and    Err.-- 

5    P.    Har::  -     iogist    in    Chr.:_ 

■tant    Plant    Breeding    Investigations.    Thomas    H.     Kearney, 

SoU  Bad  and  Water  Purification  Investigations.  Karl  F.  Kellerman.  Physiologist 

Bionoi  ;s  of  Tropical  and  Subtropical  Plants,  Orator  F.  Coot.  Bionomist 

Iture  Investigations.  Rodn-v  i: 
- 

;st  in  Charge. 
Crop   Technol  Plant  ligations,  Nathan  A.  Cohb.  Crop  Technol.  - 

_ 

omic  and  Rat.  ;;ie.  Botanist  in  Chr.:- 

Farm  Ma'  "TiHiam  J    Spillman.  Agriculturist  in  Charg 

M 

--    Horticult-: 
■  :3.m  W.  T:  S  iperinter  . 

Sugar  Tovrnsend.  Pathol   . 

Hon  Investigations.  -     ^-oneld.  Agriculturist  in  Charge. 

Agriculture  It,  Agriculturist  in  Charge. 

-         5  B.  1         cert.  1  list  i 

William  A.  Taylor  and  G.  Harold  Powell.  Pohk     -  5ta 

.^ard  M.  Byrnes.  Superintendent. 
■  i  and  Plant  Introductio'  -irchild.  Agricultural  Explorer  in   Charge. 

-  V.  Pip*r.  Agrostologist  in  Charge. 

_ 

s'r.anahan.  Crop  Technologist  in  Charge. 

Pathologist  in  Charge. 
Plant  Introduction  Garden.  Mayer.  Expert  in  Charge. 

South  Jen,  Bro  -  "dward  C  Gre*-n.  Pomologist  in  Ct     - 

Farm-  ttion  Work.  Seaman  A.   Knapp.  Special  Agent  in  < 

button   (Directed  by  Chief  of  Bureau >.  issistant  in  <• 


Editor,  J.  E.  Rock^v 
Chief  Clerk,  James  E.  J 


CON']  I. NTS. 


t  tacurrence  i  if  tumors 5 

I  >tic 'ii li 

Experiments it 

Structure  of  tumors lit 

Relation  of  the  tumors  t>>  other  forms  of  disease II 

Effecl  of  the  disease  upon  trees 12 

-i  mi i-  to  nurserymen,  nursery  inspectors,  and  orchardists 1"> 

9ired  "ii  the  distribution  and  severity  of  stem  tumors  or  knots....  I  (J 

[Cii 

3 


I  I  LIST  RATIONS 


i  - 

Fig.     !.  Stem  tumors  on  an  old  apple  tree  at  Mesilla  Park,  X.  Mex (j 

2.  si  cm  inn  Kirs  cm  a  Meech  quince  tree  at  <  Ihico,  ( !al 7 

;;.   Young  tumors  forming  at  the  base  of  twigs  on  a  Charlamori  apple 

tree  at  Fayetteville,  Ark 8 

l.  Older  tumors  than  those  shown  in   figi  .     3  on  a  <  harlamoff  apple 

tree  at  Fayetteville,  Ark it 

5.  Knots  produced  from  a  tumor  on  a  cutting  taken  from  a  Charlamoff 

apple  tree  ami  kept   in  moisl  soil 1(1 

6.  Knots  produced  from  tumors  on  a  cutting  taken  from  a  Meech  quince 

t  ree  near  Chico,  Cal It* 

7.  Longitudinal  section  of  a  tumor  on  an  apple  limb  after  throwing  out 

roots  when  placed   in  soil 11 

8.  Longitudinal   section  of   woolly-knot  on  a   root-grafted   apple   tree 

grown  from  apparently  healthy  scion  and  root 11 

9.  The  woolly-knot  form  of  hairy-root  on  a  Northern  Spy  apple  tree 

grown   in  an  experiment 1- 

10.  The   simple  form  of   hairy-root  on  an  apple   seedling    grown  in  an 

experiment L3 

1 1.  The  origin  of  hairy-root  from  buds  on  an  apple  seedling L3 

[Cir.  ::  I 

4 


B.    P.    I      :!'• 


SOME  STEM  TUMORS  OR  KNOTS  ON  All 
AND  OUINCE  TREES. 


OCCURRENCE  OF  TUMORS. 

A  peculiar  form  of  tumors  or  knots  has  been  observed  by  the  writer 
during  the  past  five  years  occurring  on  the  trunks,  limbs,  and  twigs 
of  apple  trees  (fig.  !)  and  quince  trees  (fig.  2)  in  a  number  of  local- 
ities in  various  portions  of  the  United  States.  These  localities  arc  in 
some  cases  widely  separated,  indicating  that  the  disease  may  be  found 

occurring  over  a  wide  extent  of  territory.     The  t ■-  on  the  quince 

have  been  observed  at  Chico  and  other  points  in  California,  and  re- 
ports of  their  occurrence,  with  specimens,  have  been  received  by  the 
writer  from  Ansted,  W.  Va.  Those  on  the  apple  have  been  noted  in 
:i  number  of  localities  in  California.  Oregon,  New  Mexico.  Texas, 
Arkansas,  Kansas,  Nebraska,  Iowa,  Missouri,  Ellinois,  and  West 
Virginia.  Specimens  taken  from  apple  seedling  trees  have  been 
received  from  Mr.  C.  <>.  Woodbury,  of  the  Indiana  Agricultural 
Experiment  Station,  collected  in  southern  Indiana. 

Garcia,  of  the  New  Mexico  Experiment  Stat  ion.  reports  the  disease 
on  apple  trees  from  Mesilla  Park,  Hatch,  and  Garfield,  X.  Mex. 
Garman,   of  the  Kentucky  Experi m  Station,  has  described  a  form 

is  paper  records  the  results  of  observations  and  experiments  on  a  type 
of  disease  thai  occurs  in  the  apple  and  quince  orchards  and  is  particularly 
troublesome  to  nurserymen.  The  tumors  described  are  related  to  hairy-root 
and  crown-gall,  and  this  publication  summarizes  a  part  of  an  extensive  inves- 
tigation which  Doctor  Hedgcock  is  pursuing  on  the  crown-gall  and  related  dis- 
eases. The  paper  brings  oul  some  importanl  facts  regarding  the  relation  of 
the  knots  above  ground  to  certain  forms  of  hairy-root,  and  contains  advice  to 
nurserymen  .-is  to  how  to  avoid  the  trouble.  These  investigations  were  begun 
at  the  Mississippi  Valley  Laboratory,  St.  Louis,  Mo.,  under  the  direction  of  Doc- 
tor Hermann  von  Schrenk,  and  will  I"-  continued  under  the  direct! r  Mr.  M.  B. 

VTaite,  Pathologist  in  Charge  of  investigations  of  Diseases  of  Fruits.  B.  T. 
Galloway,  Pathologist  and  Physiologist,  and  Chief  of  Bureau. 

Garman,  II.  Diseases  of  Nursery  Stock  A  Knot  Disease  of  Apple  Trees. 
Keuiu.k\  Agricultural  Experlnieul  Station,  Bulletin  03,  pp.  106-107  and  flg.  4, 
L901. 

I       :      3] 

5 


6 


SOME  STEM  TUMORS  OR  KNOTS  ON  APPLE  AND  QUINCE  TREES. 


of  knots  occurring  on   apple  trees   which   is   apparently   the   same 
disease;   this  he  reports  from   at  least  two  localities  in  the  State. 


' 

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Fig.   1 — stem  tumors  on  ;m  old  apple  tree  at  Mesilla  Park,  N.  Mex. 

Waite,  of  the  Bureau  of  Plant  Industry,  reports  the  disease  as  com- 
mon on  the  apple  in  tidewater  Maryland  and  Virginia. 

DESCRIPTION. 

On  the  apple  tree  this  disease  appears  most  often  oil  the  trunk  and 
larger  limbs  (fig.  1),  but  in  a  number  of  instances  it  has  been  found 

[Cir.3] 


SOME  STEM  TUMORS  OR  KNOTS  ON    VPPL1     VND  QUINCE    FREES 


affecting  the  twigs  and   smaller  1  iml >~    (fig.  3),     A   g I  example 

of  the  disease  as  found  on  all  parts  of  the  tr< ccurs  on  a  Charlamoff 

apple  tree  in  the  experimental  orchard  <>f  the  Arkansas  Agricultural 
Experiment  Station,  Fayetteville,  Ark.  This  was  first  reported  to 
the  Bureau  of  Plant  Industry  by  Vincenheller,  of  that  station,  who 
kindly  donated  the  tree  to  the  Department  of  A.griculture  for  further 


Fig.   -      Stem  tumors  on  a  Meech  quince  tree  al  Cuico,  <':ii 

study.     The  progress  of  the  disease  on  this  tree  has  been  noted  for 
three  successn  e  years. 

The  tumors  on  this  tree  arc  exceptionally  large  at  the  beginning, 
and  frequently  appear  in  the  form  <>l'  a  smooth  swelling  surrounding 
the  base  of  a  dormanl  bud   (fig.  3),  quite  often  the  terminal  bud  of 

[Clr.  3] 


8  SOME  STEM  TUMORS  OR   KNOTS  ON   APPLE  AND  QUINCE  TREES. 


a  twig,  and   may  be  noted  at  the  end  of  the  growing  season.     In 

the  form  usually  occurring  on  many  other  trees,  the  swellings  appear 
on  twigs  and  limbs  indiscriminately,  apparently  having  no  connec- 
tion with  the  formation  of  buds.  The  tumors  vary  greatly  in  size 
on  the  same  and  on  different  trees;  some  are  as  small  as  a  pea: 
others  attain  a  size  of  2  to  3  inches  in  diameter.  This  variation 
in  size  is  noted  even  at  the  beginning  of  the  formation.  Imma- 
ture tumors  are  often  formed  on  all  por- 
tions of  the  tree,  quite  frequently  occurring 
at  the  base  of  twigs  (fig.  ?>)  or  springing 
from  older  limbs  or  from  the  trunk.  Dur- 
ing the  first  period  of  their  growth  the 
swellings  are  covered  with  a  thick,  fleshy 
layer  of  meristem  and  bark  tissues.  The 
growth  for  the  first  year  or  two  i-  often 
very  rapid.  At  the  end  of  a  varying  period 
of  time,  usually  one  to  three  year-,  depend- 
ing on  the  variety  of  the  tree  and  the  condi- 
tions of  growth  in  the  locality  where  it  i- 
found.  the  bark  covering  the  tumors  be- 
comes ruptured  by  the  rapid  formation  in 
the  interior  of  a  very  peculiar  structure; 
the  bark  tissue  ceases  to  grow,  hut  the  inte- 
rior tissues  develop  a  structure  similar  to 
that  found  in  root  formation  in  the  hairy- 
root  disease.  As  the  bark  breaks  away, 
small  elevations,  -which  resemble  short 
thickened  root  caps,  appear  on  the  surface 
of  the  tumors,  giving  them  a  very  warty  ap- 
pearance (fig.  4).  The  knots  now  resemble 
I  he  origin  of  the  formation  of  the  woolly- 
knot  form  of  hairy-root  described  by  the 
writer"  in  a  lecture  to  the  National  Nursery- 
men's Association  last  year. 

The  tumors  in  their  older  form  in  some 
cases  become  hollowed  out  by  a  slight  decay 
of  the  tissue  in  the  center,  which  results 
either  directly  from  the  disease  or  from  the  entrance  of  wood-rotting 
organisms  which  are  foreign  to  it.  The  mature  form  of  these  knots 
( lie;.  1)  resembles  greatly  the  outgrowths  upon  the  limbs  of  a  num- 
ber of  kinds  of  trees  described  by  Sorauer6  in  Germany  under  the 


■- 


FlG.  '■'>. — Young  tumors  form- 
ing at  the  base  of  twigs  on 
a  Charlamoff  apple  tree  al 
Fayetteville,  Ark. 


<*Hedgcock,  George  <;.  Prevention  of „  Apple  Crown-Gall  and  Hairy-Root. 
National  Nurseryman,  vol.  15,  pp.  192-193,  1907.  American  Fruits,  vol.  T.  p. 
69,    1907.     Apple  Specialist,  vol.    I.  pp.   II    15,   1907. 

6  Sorauer,   r.     Kropfmaser.     Handbucb  der   Pflanzenkrankheiten,  vol.  1.  pp. 
7::i  t::i  ami  fig.  :;s,  1886. 
[Cir.  3] 


SOME  STEW    rUMORS  OR  KNOTS  OK    U'IM.l     IXD  QUINC1     I 


9 


name   of    Kropfmaser,    with    which    form    of   disease   they    may   be 
identical.     A   similar   form  on  Pirns  mains  chinensis  has  been   de 
scribed  by  Kissa. 

On  the  quince  tree  the  disease  originates  quite  similarly  to  thai 
already  described  on  the  apple  tree,  with  the  exception  that  tumors 
not  been  noted  affecting  the  end  and  base  of  small  twigs.  The 
disease  appears  first  in  the  form  of  small  swellings  on  various  por- 
tions of  the  limbs  and  twigs  of  the  trees.  In  a  year  or  two  the 
fleshy  bark  of  these  is  broken  open  by  the  formation  of  num< 
root  like  structures,  and  the  tumors  assume  a  Mack,  roughened  ap- 
pearance, but  resemble  greatly  in 
strucl  ure  the  older  forms  described 
on  the  apple  tree.  These  peculiar 
outgrowths  (fig.  2)  are  often  ren 
numerous  on  the  limbs  and  trunks 
ot'  quince  trees. 

EXPERIMENTS. 

A  number  of  limit-  diseased  simi- 
larly to  those  shown  in  figure  2 
wer<  taken  from  quince  trees  at 
Chico,  Cal.,  and  others  similar  to 
those  shown  in  figures  1.  3,  and  1 
were  taken  from  an  apple  tree  at 
Fayetteville,  Ark.,  and  entirely  cov- 
ered with  moist  soil  at  the  Mis 
souri  Botanical  Garden,  St.  Louis, 
Mu..  during  the  month  of  March, 
1906.  A  fter  these  had  been  covered 
with  moist  soil  for  about  four 
week-  they  were  taken  out,  and  a 
number  of  the  tumors  had  pro- 
duced root-  in  abundance  from  the 

surface  (figs.  ■'•  and  6),  bul  no  roots  were  thrown  out  from  any  other 
portion  of  the  limbs.  In  the  case  of  the  apple  limbs  each  of  these 
knots,  after  the}  had  developed  roots  from  I  to  2  inches  in  length 
from  further  growth  in  the  soil,  agreed  in  appearance  and  structure 
with  the  knot-  occurring  in  connection  with  one  form  of  the  hairy- 
root  disease  of  the  apple,  known  as  the  woolly-knot  form  (see  fig.  9). 

In  February,  1907,  -cum-  were  taken  from  the  Charlamoff  tree  pre- 
vioush  mentioned,  some  of  which  contained  knot-  or  tumor-  like  those 


Fig.    I.     Older  tumors  than  those  shown 
in  figure  ■".  on  a  Charlamoff  apple  tree 
lyetteville,  Ark. 


Kissa,   V   w.     Kropfmaserbildung  bei   Ptrus  malus  ehinei 
fii i-  Pilanz  ?nkrankhelten,   vol.  10,  pp.   129   132  and  2   plates,    1900. 
[Clr.  Z] 


Zeltschrift 


10       SOME  STEM  TUMORS  OR  KNOTS  ON   APPLE  AND  QUINCE  TREES. 

shown  in  figure  '■'>.  while  others  were  smooth  and  apparently  healthy. 
About  70  per  cent  contained  no  knots  or  tumors;  these  were  grafted 
on  piece  roots  from  healthy  apple  seedlings.  One  hundred  of  these 
grafts  were  planted  and  grown  on  the  Potomac  Flats,  near  Washing- 
ton, D.  C.  The  trees  grown  from  these  were  dug  at  the  end  of  the 
season,  and  69.3  per  cent  were  found  to  be  diseased  to  a  greater  or 


Pig.  5. — Roots  produced  from 
a  tumor  on  a  cutting  taken 
from  a  Charlamoff  apple  tree 
and  kept  in  moist  soil. 


Fig.  6. — Roots  produced  from  tu- 
mors on  a  cutting  taken  from  a 
Meech  quince  tree  near  Chico,  Cal. 


less  degree  with  the  woolly-knot  form  of  the  hairy-root  disease.  The 
remaining  trees  were  apparently  healthy,  having  smooth  roots. 
Those  scions  which  had  tumors  before  planting  developed  in  nearly 
every  instance  root-  from  the  tumors,  which  then  agreed  in  structure 
and  appearance  with  the  woolly-knot  form  of  hairy-root. 


STRUCTURE    OF    TUMORS. 

If  a  section  is  made  longitudinally  through  one  of  the  tumors 
taken  from  the  limb  of  an  apple  tree  after  root-  have  been  forced 
from  it  by  moisture  (fig.  7)  and  through  one  of  the  underground 
rooted  tumors  of  the  woolly-knot  form  of  hairy-root  (fig.  8),  an 
identical  structure  is  revealed.  The  wood  elements  of  both  are  much 
distorted  and  disarranged,  growing  somewhat  in  a  fan  shape  from 
the  origin  of  the  tumor-  near  the  center  of  the  stem  or  root.  The 
[Cir.3] 


SOME  STEM    M    MORS  OB    KNOTS  ON    \1TI.I     I.ND  QUINCE  TREES. 


11 


bundle-  nf  wood)   tissue  are  mingled  abnormally  with  small  patches 
of  parenchymatous  tissue.     Springing  from  the  surface  of  each  of 


[ 

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r  4—            >  M 

^ngjgic^S* 

^ 

-s^^^^A 

V 

JlXl^v/)u£ 

\ 

^sj 

I'  xJw/^t/ 

V 

Fig.  7.  Longitudinal  section  of 
a  tumor  on  an  apple  limb  after 
throwing  out  roots  when  placed 
in  soil. 


s. —Longitudinal  section  of  vvoolly-knol  on  a 
root-grafted  apple  tree  grown  from  apparently 
healthy  sciuu  and  c 


these  forms  are  numerous  fleshy  roots  which  are  often  fasciated  and 
distorted.  These  fleshy  roots  as  they  grow  older  either  rot  away  in 
part  or  become  \\  oody. 

RELATION    OF    THE    TUMORS    TO    OTHER    FORMS    OF    DISEASE. 

With  our  present  knowledge,  therefore,  and  as  a  result  of  the  ob- 
servations and  experiments  previously  mentioned,  these  tumors  on 
the  limbs  and  trunk-  of  apple  trees  may  be  considered  the  same  disease 
as  the  woolly-knot  U»\w  (fig.  9)  of  hairy  root;  in  other  word-,  they 
are  the  aerial  form  of  hairy-root.  The  simple  form  of  hairy-root, 
which  was  described  first  by  Stewart,  Rolfs,  and  Hall"  and  men- 
tioned later  by  the  writer     as  a   form  of  disease  distinctly  differenl 

"Stewart,  1\  •'..  Rolfs,  I".  M.,  and  Hall,  F.  11.  Geneva,  V  v..  Agricultural 
Experiment  Station  Bulletin  191,  pp.  300  301  and  pi.  ■_'.  1900;  also  Geneva,  V  5  .. 
Agricultural  Experinienl  Station  Report  lit.  pp.  IT*',  its  and  pi.  2','..  1901. 

'■  Hedgcock,  George  <;.     The  Crown-Gall  and  Hairy  [tool   Diseases  of  the  Ap 
pie  Tree.     Bureau  of  Plant  Industry  Bulletin  No.  90,  Pari  [I,  pi.  •_'.  fig.  I,  and 
pi.  3,  lii:.  2,  1905. 
i   i  .3  | 


12       SOME  STEM  TUMORS  OR  KNOTS  ON   APPLE  AND  QUINCE  TREES. 


from  crown-gall,  is  in  the  opinion  of  the  writer  only  a  form  of  the 
same  disease  as  woolly-knot  and  these  aerial  tumor-.  The  simple 
form  of  hairy-root  occurs  most  frequently  upon  seedling  trees:  it  is 
present  both  on  the  stem  and  root  portions  of  the  trees.  It  consists, 
when  it  occurs  on  the  roots,  of  numerous  fine  roots  growing  at  right 

angles  from  the 
main  roots  or  the 
taproot  (fig.  10). 
These  side  roots 
arc  very  soft  and 
succulent  at  first. 
but  later  harden 
and  have  a  wiry 
appearance  and 
texture.  On  the 
roots  they  arc 
usually  quite  uni- 
formly distributed 
in  definite  belts. 
Where  this  form 
occurs  on  shoots  it 
springs  more  fre- 
quently from  the 
vicinity  of  a  bud 
(fig.  11),  often  just 
beneath  it.  These 
fine  roots  are 
formed  in  groups, 
or  bunches,  a 
great  many  often 
springing  from  a 
single  origin. 
The  origin  of  each  of  these  clumps  of  roots  is  similar  to  that  of  the 
rudimentary  roots  in  the  aerial  tumors.  It  follows,  then,  that  the 
hairy-root  disease  may  have  at  least  three  forms,  which  are  more  or 
less  distinct:  The  simple,  the  woolly-knot,  and  the  aerial  forms. 

EFFECT  OF  THE  DISEASE  UPON  TREES. 

Owing  to  the  complexity  in  the  forms  of  the  hairy-root  disease 
and  the  difficulty  of  obtaining  accurate  information  as  to  their  final 
effed  upon  orchard  trees,  and  in  view  of  the  fact  that  extensive  ex- 
periments are  being  conducted  to  determine  the  nature  of  each  form 
and  its  effect  upon  the  life  and  fruit  fulness  of  apple  trees,  it  will  not 
he  safe  at  present  to  make  a  definite  statement  as  to  the  effect  of  these 
tumors  further  than  to  give  the  observations  of  the  writer. 

ICir.  3] 


Fig.  9. 


-The  woolly-knot  form  of  hairy-root  on  a  Northern  Spy 
apple  tree  grown  in  an  experiment. 


SOME  STEM    CUMORS  OR    KNOTS  ON    UM'l.i     i.ND  QUINCE  TREES.        l',\ 


A.pple  trees  from  fifteen  to  twenty  year-  old  badly  diseased  with 
these  tumors  have  been  observed  in  various  localities  in  the  Missis 
sippi  Valley.  The  cores  of  the  tumors  ex- 
tended nearh  to  the  hearl  or  center  of  the 
wood  of  the  largest  limbs,  indicating  that 
the  tumors  had  been  present  during  the  life- 
time of  the  trees.  Upon  inquiry,  the  owners 
claimed  that  such  trees  usually  bore  as  well  as 
other  trees  in  the  orchard,  and  from  all  indi- 
cations tln\  were  making  a-  good  growth  as 
other  i  iv,-.  Tin'  knots  were  apparently  sound 
throughout,  and  a-  far  a-  could  be  observed 
did  no  damage  to  the  tree  other  than  to  ob- 
struct tli«'  circulation  to  some  extent.  This 
interference  with  the  circulation  of  the  tree, 
however,  can  not  be  considered  beneficial  I  • 
it-  grow th. 

Waite,   of   the    Bureau   of   Plant    Industry, 
ha-  observed  in  many  instances  thai  the  ecu 

ters  of  old  tumor-  on 
mature  apple  tree 
ten  decay,  either  di- 
rectly as  a  resull  of 
tin-  disease  or  through 
the  entrance  id'  organ- 
isms which  may  seriously  injure  the  tree. 
The  climate  and  condition-  of  the  Atlantic 
coast,  where  Waite  made  hi-  observations,  are 
different  from  those  in  which  the  writer's 
observations  were  made,  and  this  may  ac- 
count in  some  measure  for  the  different  ef 
feet  observed. 

A    Study    of   the   effects    of   the    forms   of   the 

disease  occurring  on  the  root-  of  the  apple 
tree  is  in  progress  and  it  is  hoped  that  the 
results  may  l>e  published  later.  Some  of  these 
results  are  very  peculiar;  for  instance,  the 
writer  was  surprised  to  find,  in  planting  out  in 
■'";    n      ''''"'  origin  of   an  orchard  under  the  same  condition-  during 

halry-rool  from  buds  mi  an  ,  ,  _  . 

appi, dung,  ;>  very  dry  season  about    . « m »  apple  tree-,  one 

hall   of  which  had   root-  diseased   with  hair\ 
font   of  tl„.   woolly-knol    type   (fig.  9)    and   the  other  half  healthy. 
smooth  root-,  that  a  greater  -land  of  trees  was  obtained  with  the  for 
mer.    The  loss  in  the  case  of  the  hair\  pool  trees  was  aboul  19  per  cent, 

[Clr.  3] 


Fig.  10.  The  simple  form  of 
hairy  roo  t  mi  a  a  a  pp  I  e 
sei  dling  grown  in  an  ex- 
periment. 


14       SOME  STEM  TUMORS  OE  KNOTS  ON  APPLE  AND  QUINCE  TREES. 

and  of  the  trees  with  smooth  roots  about  :'>•_!  per  cent.  This  may  be 
accounted  for  in  part  by  the  increased  tendency  to  throw  out  roots 
in  the  case  of  the  trees  diseased  with  hairy-root. 

This  peculiar  behavior  on  the  part  of  trees  diseased  with  hairy- 
root  is  further  explained  by  another  experiment.  Since  apple  trees 
are  propagated  commercially  by  grafting  and  budding,  never  by 
cuttings,  because  they  root  so  rarely,  it  was  a  surprise  to  find  that 
cuttings  from  trees  with  hairy-root  are  often  able  to  throw  out  roots 
readily.  In  an  experiment  where  100  cuttings  were  taken  from  the 
shoots  of  yearling  seedlings  badly  diseased  with  the  simple  form  of 
hairy-root  (fig.  10)  and  planted  in  moist  soil  in  the  greenhouse  in 
early  spring,  more  than  50  per  cent  rooted  readily  and  25  per  cent 
grew  into  trees.  On  the  other  hand,  out  of  100  cuttings  taken  from 
healthy  seedlings  of  the  same  lot,  only  5  per  cent  rooted,  and  even 
then  so  feebly  that  none  of  them  grew  into  trees.  This  experiment 
was  carried  out  on  an  ordinary  greenhouse  bench  with  8  inches  of  soil, 
without  bottom  heat. 

Some  of  the  diseased  quince  trees  observed  by  the  writer  in  Cali- 
fornia were  much  stunted  in  their  growth,  but  were  considered  a 
profitable  investment  by  the  owner  on  account  of  the  crops  of  fruit 
which  they  had  borne  for  several  years.  The  quince  trees  in  Cali- 
fornia appear  to  be  quite  universally  affected  with  this  disease, 
though  usually  with  only  a  mild  form.  Xo  indication  has  been  found 
that  the  disease  spreads  in  the  orchard  from  one  tree  to  another, 
either  in  the  case  of  apple  or  quince  trees,  and  experiments  in  which 
inoculations  were  made  with  chips  from  living  tumors  indicate  that 
it  is  either  very  little  or  not  at  all  contagious.  In  the  case  of  apple 
trees,  the  percentage  of  disease  on  the  roots  of  trees  in  nursery  rows 
increases  perceptibly  from  the  first  to  the  second  year  and  remains 
i  he  same  or  decreases  from  the  second  to  the  third  year.  This  observa- 
tion  is  based  upon  an  extensive  experiment. 

It  might  easily  be  true  that  a  reasonable  amount  of  this  disease 
on  a  tree  stimulates  it  and  encourage-  fruit  production.  That  it  does 
stimulate  root  production  and  may  temporarily  stimulate  the  growth 
of  the  tree  are  facts  now  well  known  to  the  writer  and  have  been  ob- 
served in  many  instances  in  the  case  of  nursery  trees.  The  disease, 
therefore,  appears  to  be  not  as  injurious  as  one  would  think.  It  can 
hardly  be  possible,  however,  that  in  the  long  run  trees  seriously 
affected  by  this  disease  will  not  sutler.  Branches  badly  affected, 
as  shown  in  figures  1  and  '_!,  certainly  must  have  their  movement  of 
sap  greatly  impeded,  their  general  activities  much  curtailed,  and 
eventually  their  life  shortened.  It  is  not  believed,  however,  that  small 
tufts  of  hairy-roots  on  very  limited  areas  of  the  root  system  of  an 
apple  tree  will  in  any  way  perceptibly  affect  the  growth  and  fruit- 
fulness  of  an  apple  tree  or  decrease  its  length  of  life, 
rcir.  ::j 


SOME  STEM    rUMORS  OR  KNOTS  ON    iPPLE  AND  QUINCE    FREES.        L5 

SUGGESTIONS     TO     NURSERYMEN,     NURSERY     INSPECTORS.     AND 

ORCHARDISTS. 

Nurserymen  are  ad\  ised  to  be  careful  in  the  selection  of  scions  and 
stocks  for  propagation  and  to  see  thai  they  are  always  taken  from 
health}  trees.  The  experiments  of  the  writer  in  the  case  of  1 1 1  *  -  apple 
indicate  that  all  forms  of  hairy-rool  on  scions  increase  where  the 
scions  arc  taken  from  diseased  trees. 

The  following  suggestions  based  upon  experiments  and  observa 
bions  arc  made  to  nursery  inspectors:  Apple  or  quince  trees  badly 
diseased  with  any  of  the  forms  of  hairy-root,  whether  aerial,  woolly- 
knot,  or  simple,  should  be  discarded  as  unfit  for  planting.  Figures 
1.  ■_'.  3,  l.  '•'.  and  LO  represent  severe  tj7pes  of  aerial,  woolly-knot,  and 
simple  forms  of  hairy-root.  The  last  two  forms  occur  on  the  root-  of 
trees  in  the  nursery,  while  the  first  is  found  as  a  rule  only  on  orchard 
trees,  probably  as  a  later  development  of  the  more  intense  forms  of 
the  disease  on  the  root s. 

[f  all  trees  affected  with  traces  or  milder  forms  of  the  disease  as  it 
occurs  on  the  roots  were  discarded,  it  would  mean  the  rejection  of 
nearly  all  of  the  tree-  grown  in  some  localities.  Such  trees  when  they 
have  a  vigorous  root  system,  notwithstanding  trace-  or  mild  forms  of 
the  disease,  apparently  grow  as  well  a-  healthy  trees  with  smooth 
roots,  or  in  some  cases  may  grow  better  for  the  first   few  year-,  so  far 

as  ha-  I n  ascertained  l>\  experiments  and  observations.    Until  it  can 

he  shown  that  the  piv-ciicc  of  the  milder  form-  of  the  disease  on  the 
root  -  of  nursery  tree-  will  lead  to  it-  further  spread  in  the  orchard,  or 
that  such  tree-  arc  unprofitable  for  planting,  it  doc-  not  seem  justifia 
ble  to  condemn  them.     On  the  other  hand,  the  writer  is  not  ready  to 
assert  that  they  are  equally  as  good  for  planting  as  trees  with  smooth 

loot-. 

There  is  a  difference  of  opinion  as  to  what  constitutes  a  healthy 
root  system;  some  would  limit  the  application  of  the  term  "  healthy  v 
to  tree-  entirely  free  from  fibrous  root  formation  on  the  main  rout-. 
The  writer  has  observed  that  trees  with  a  very  fibrous  root  system 
are  often  the  product  of  certain  kinds  of  soil  and  arc  apparently  as 
healthy  as  tree-  more  nearly  free  from  such  roots.  Such  tree-  are 
equally  as  good  for  planting  as  those  with  smooth  root-  and  might 
easily  be  mi-taken  for  diseased  tree-  slightly  affected  with  trace-  of 
hairy  root.      Until   it   can   be  -how  n   that    librou-  root-   arc   inferior  to 

-i th  roots  and  that  the  milder  forms  of  hair}  root  seriously  affect 

orchard  trees,  the  writer  is  not  ready  to  recommend  the  destruction 
of  such  trees  in  the  nursery,  since  this  course  would  probably  involve 
an  unnecessary  loss  of  many  thousands  of  dollars  to  the  nurserymen 
and  a  consequent  increase  in  the  price  of  trees  to  the  orchardists. 

[Clr.  3] 


16       SOME  STEM   TUMORS  OK  KNOTS  ON   APPLE  AND  QUINCE  TREES.  ' 

Reports  have  been  received  from  a  number  of  localities  where  all 
the  trees  in  orchards  affected  by  these  tumors  ( fig.  1)  have  been  cut 
down  on  account  of  their  presence.  In  the  absence  of  data  proving 
the  disease  to  be  seriously  injurious  and  in  view  of  the  writer's  ob- 
servations, orchardists  are  advised  for  the  present  to  allow  such  trees 
to  remain  in  their  orchards  in  cases  where  there  is  no  apparent  spread 
of  the  disease  and  where  the  trees  are  bearing  profitable  crops  of 
fruit.  If,  on  the  other  hand,  the  trees  are  not  doing  well  as  compared 
with  healthy  trees,  it  would  be  better  to  remove  them. 

REPORTS    DESIRED    ON    THE    DISTRIBUTION    AND    SEVERITY    OF 
STEM     TUMORS     OR     KNOTS. 

It  will  readily  he  seen  that  further  information  as  to  the  distribu- 
tion and  severity  of  this  disease  is  needed.  To  this  end  it  is  proposed 
to  visit  as  many  localities  as  possible  where  outbreaks  of  the  disease 
are  reported. 

All  persons  who  have  observed  stem  tumors  or  knots  in  orchards 
will  confer  a  favor  and  will  aid  in  accumulating  data  if  they  will 
report  the  localities  where  the  disease  occurs,  with  notes  as  to  its 
severity.  All  communications  should  he  addressed  to  the  Bureau  of 
Plant  Industry.  U.  S.  Department  of  Agriculture.  Washington,  D.  C. 

Approved:  mlllMMill 

James  Wilson, 

Secretary  oj  Agriculture.  3  1262  08929  0042 

Washington,  D.  C,  April  1.  1908. 

[»'ir.  3] 

o 


